home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Space Science Sampler 2
/
NASASpaceScienceSamplerV2.cdr
/
ocean
/
ocean.txt
< prev
next >
Wrap
Text File
|
1987-04-08
|
3KB
|
74 lines
NJPL1I00PDS000000000
FILE_TYPE = TEXT
RECORD_TYPE = STREAM
END
Ocean data sets for CDROM.
As stated, each file has 512 x 512 pixels which form an image.
Each pixel is represened by one byte, each scan of the image by
one record. The possible data values for any pixel, therefore,
range from 0 - 255.
For displaying the images, the only constraint we have is that
data value 0 should be black and 255 should be white. This is
because all images have textual information scribed in to make
them self-documenting. If it is impossible to accomodate this
color scheme, the only loss will be that the text may be of low
contrast or invisible. Text (data value 255) is always written
against a background of data value 0.
All data values other than 0 and 255 represent linearly scaled
geophysical values. That is, the greater the data value in the
image, the greater the geophysical value. For display, we
typically use a color scheme where the colors grade gradually and
linearly from 0 to 255:
black - magenta - purple - blue - cyan - green - yellow - red -
white.
This gives a pleasing effect for sea surface temperature data,
where purples and blues (cool colors) represent colder waters,
and yellows and reds the warmer waters. You may change the color
representation as you see fit, but that is how we do it. Some of
the images have a scale included that relates the displayed color
to its corresponding geophysical value. This is done to make the
images more self-documenting.
The data files we selected are:
WCSNAP.IMG - chlorophyll concentration of the easterm pacific
from 20N to 55N (U. S. Pacific Coast). 1 pixel is about 10 km
square. The image includes a scale for translating color to
geophysical value, so any color scheme can be used for display.
WCMEAN.IMG - A monthly mean of images like the above. Scale
included.
SCBSST.IMG - A sea surface temperature image from the Santa
Barbara area. A ship track is also shown on the image. Scale
included. 1 pixel is about 1 km square.
SCBSNAP.IMG - a chlorophyll concentration image from the Santa
Barbara area. Scale included. 1 pixel is about 1 km square.
SCBMEAN.IMG - A monthly mean of images like the above. Scale
included.
LI.IMG - A chlorophyll concentration image from the New York
City area. 1 pixel is about 1 km square. No color scale.
GS.IMG - A sea surface temperature image of the western Atlantic
showing the sharp thermal boundary of the Gulf Stream. 1 pixel
is about 10 km square. No color scale.
GLOBAL.359 through GLOBAL.240 - these files are a "movie" of the
global (full earth disk) sea surface temperature over a 2-week
period. If the frames are displayed in sequence, the earth will
appear to rotate. They are stored in order 359 - 240 because
that sequence causes the motion to be in the "right" direction.
There are a total of 127 * 512 * 512 bytes (31.75 megabytes) of
data.